The present invention relates to a tubular water wheel and, more particularly, to a tubular water wheel with a device for actuating runner vanes thereof being arranged outside of the water wheel.
A tubular water wheel may be operated with a high efficiency over a wide operational range by controlling an angle of the runner vanes thereof in accordance with its operational condition. A hydraulic pressure is generally used as a power source for the runner vanes.
Accordingly, in order to actuate the runner vanes to change their operational angle, a hydraulic pressure is applied through a water wheel main shaft to a servomotor disposed in a runner boss by means of a hydraulic pressure feeder arranged within stay vanes. As a result, the runner vanes which are rotatably mounted on the runner boss are actuated through a link connected to the servomotor.
In the thus constructed tubular water wheel, the space in the runner boss is large, which is suitable for a large capacity machine having an output of several ten thousands of kilo watts. However, in case of a small capacity machine having an output of several hundreds of kilo watts, the space in the runner boss is small. Therefore, in this case, it is impossible to use a built-in type servomotor and hence a tubular water wheel as disclosed in, for example, the Japanese Patent Publication No. 58-4238 is available in which its runner vane actuator is disposed outside of the water vane.
FIGS. 3 and 4 show the tubular water wheel with an actuator for operating runner vanes being arranged outside of the tubular water. The tubular water wheel includes a draft tube 1, stay vanes 2, a stay ring 3, a wheel inner case 4, guide vanes 5 for adjusting and guiding the flow of water, a water wheel main shaft 6, a guide bearing 7 for the water wheel main shaft 6, a runner boss 8, runner vanes 9, an operating rod 10 for the runner vanes 9, a cross head 11, a link 12, a lever 13, a runner vane rotary shaft 14, a rotary disc 15 loosely engaged with the operating rod 10, a spiral fixed member 16 for forming (together with a part of the water wheel inner case 4) a spiral engagement groove 17 engaged with the rotary disc 15, an operating rod 18 one end of which is rotatably mounted on a pin 19 implanted in the rotary disc 15 and the other end of which is rotatably mounted at one end of a lever 21 rotatably mounted about a pin 20 outside of the tubular passage, and a servomotor 22 for applying its operating power to the other end of the lever 21.
With the thus constructed tubular water wheel, pressurized water fed through the stay ring 3 is applied through the guide vanes 5 to the runner vanes 9 and is discharged through the draft tube 1 to the downstream side, whereupon the runner vanes 9 are rotated to actuate an electric generator (not shown) directly coupled to the water wheel main shaft 6, thereby generating an electric power. When the servomotor 22 is actuated to allow the rotary disc 15 to be rotated through the operating rod 18, the rotary disc 15 may be reciprocatingly moved rightward and leftward as shown by the phanton line in FIG. 3 because the rotary disc 15 is engaged with the spiral engagement groove 17. As a result, the operating rod 10 is also reciprocated right and left whereby the angle of the runner vanes 9 mounted rotatably on the runner boss 8 through the cross head 11, the link 12 and the lever 13 may be adjusted to any desired angle.
However, in order to change and keep the angle of the runner vanes 9 of such a tubular water wheel, a large force is required. Even in case of the smaller capacity machine having an output power of several kilo watts, since an operating force of several tens of tons is applied to the rotary disc 15 and the operating rod 10, a frictional loss would become marked. More specifically, in such a tubular water wheel, the up and down motion of the operating rod 18 must be converted into the right and left reciprocating motion by means of the spiral engagemnet groove 17, and there must be provided a coupling structure subjected to the propelling force of the operating rod 10 to be rotated together with the runner vanes 9 and the runner boss 8 and to be reciprocatingly moved right and left together with the rotary disc 15. Thus, the two bearing portions are needed for being subjected to the operating propelling force and rotation of the operating rod 10. Therefore, large frictional losses would be generated in the respective sliding parts due to such a complicated mechanism for converting the up and down motion of the operating rod 18 through the spiral engagement groove 17 into the right and left reciprocating motion, and the spiral engagement groove portion would be damaged due to its scratching or a seizing phenomenon. The complicated mechanism is difficult to assemble and disassemble. Because the two bearing portions are subjected to the operating propelling force and rotation and the guide bearings for the water wheel main shaft are separately provided, a problem will be encountered that the oil feeding portions must be separately provided for the various bearing portions.